Marine lipids
development in embryos and adults. According to Merican & Shim
(1997), the growth response and survival in juvenile shrimp were
improved with 18:3 at 1.5 and 2.5%, and 22:6 at 1.5 and 2.0% supplementation of diets, provided by cod liver oil. However, to our knowledge, neither maximal PUFAs concentration tolerance, nor toxic effects
due to the other PUFAs are mentioned in literature. During phytoplankton development in dense quasi-monospecific blooms occurring
in coastal waters, noxious and deleterious effects are often observed on
fauna (Erard-Le Denn et al., 1990) and flora (Lindahl & Dahl, 1990).
Chemical composition of lipid content in the corresponding algal cells,
revealed high amounts of long-chain PUFAs, mainly glycolipids and free
acids classes (Ackman et al., 1968). The strains isolated during the
toxic events and maintained in optimal condition growth, presented
unmodified composition (Bodennec et al., 1995). It appeared relevant
for aquaculture purpose to compare the fatty acids composition in the
algae and their effects on some antagonist organisms for the cells: bacteria, algal competitors, algal consumers. The objective of this work was,
through the ichthyotoxic alga Gymnodinium mikimotoi, to check the phytoplanktonic PUFAs toxicity towards marine organisms, and extend the
model to other phytoplankton genus.
Material and methods
Algal cultures
The toxic strain used in the study was obtained by isolation of planktonic cells during the toxic event in Brittany (France): Gymnodinium mikimotoi in 1987. Pavlova lutherii and Phaeodactylum tricornutum strains
were kindly provided by the Département des ressources vivantes of
Ifremer. The algae were grown axenically in f/2 medium, at temperature 18°C and under 12 h ligh/dark cycle at 75 μmol.m - 2 .s - 1 . The
cultures were performed in oceanic water at salinity 34, previously
treated by filtration through C18 and Florisil SepPak® cartridges
(Waters) to obtain constant chemical quality, then sterilized at 60°C
during 20 minutes.
PUFAs analyses
At the end of the exponential growth stage of the culture, the cells
were concentrated by gravity filtration through precombusted Whatman GF/F filters. Lipid fractions were extracted following Parrish et al.
method (1993). The chemical analysis was realised by means of Chromarod-Iastroscan® system for chemical classes determination (Bodennec et al., 1995), and GC/FID for identification and quantification of
fatty acid components.
During an ichthyotoxic bloom occurred in 1994 in Étang de Diane (Corsica, France), time series samples were collected for one month. Floristic
composition was compared to the fatty acid composition of the sample.
54
development in embryos and adults. According to Merican & Shim
(1997), the growth response and survival in juvenile shrimp were
improved with 18:3 at 1.5 and 2.5%, and 22:6 at 1.5 and 2.0% supplementation of diets, provided by cod liver oil. However, to our knowledge, neither maximal PUFAs concentration tolerance, nor toxic effects
due to the other PUFAs are mentioned in literature. During phytoplankton development in dense quasi-monospecific blooms occurring
in coastal waters, noxious and deleterious effects are often observed on
fauna (Erard-Le Denn et al., 1990) and flora (Lindahl & Dahl, 1990).
Chemical composition of lipid content in the corresponding algal cells,
revealed high amounts of long-chain PUFAs, mainly glycolipids and free
acids classes (Ackman et al., 1968). The strains isolated during the
toxic events and maintained in optimal condition growth, presented
unmodified composition (Bodennec et al., 1995). It appeared relevant
for aquaculture purpose to compare the fatty acids composition in the
algae and their effects on some antagonist organisms for the cells: bacteria, algal competitors, algal consumers. The objective of this work was,
through the ichthyotoxic alga Gymnodinium mikimotoi, to check the phytoplanktonic PUFAs toxicity towards marine organisms, and extend the
model to other phytoplankton genus.
Material and methods
Algal cultures
The toxic strain used in the study was obtained by isolation of planktonic cells during the toxic event in Brittany (France): Gymnodinium mikimotoi in 1987. Pavlova lutherii and Phaeodactylum tricornutum strains
were kindly provided by the Département des ressources vivantes of
Ifremer. The algae were grown axenically in f/2 medium, at temperature 18°C and under 12 h ligh/dark cycle at 75 μmol.m - 2 .s - 1 . The
cultures were performed in oceanic water at salinity 34, previously
treated by filtration through C18 and Florisil SepPak® cartridges
(Waters) to obtain constant chemical quality, then sterilized at 60°C
during 20 minutes.
PUFAs analyses
At the end of the exponential growth stage of the culture, the cells
were concentrated by gravity filtration through precombusted Whatman GF/F filters. Lipid fractions were extracted following Parrish et al.
method (1993). The chemical analysis was realised by means of Chromarod-Iastroscan® system for chemical classes determination (Bodennec et al., 1995), and GC/FID for identification and quantification of
fatty acid components.
During an ichthyotoxic bloom occurred in 1994 in Étang de Diane (Corsica, France), time series samples were collected for one month. Floristic
composition was compared to the fatty acid composition of the sample.
54